Phase 90 mods

[tuberattler]

Where's the best place to find info on these pedals?

I'm trying to find a schemo or layout of the modern (new) Phase 90. I'm wanting to do the R28 mod that I've read about but I need a schem or picture or layout..something to locate the resistor in question.

[tuberattler]

Since I'm talkin to myself I found the modern Phase 90 Layout via a friend. It's at Youlsa.com which is in Korea. You'll have to Google and have them convert the page to English.

So, I modded the Phase 90 R28 by lifting one leg off the circuit board and wow what a great difference and pedal after the mod. Very usable!!

Now, why doesn't MXR make this pedal with out that resistor?? It's not very usable with it in the circuit..

BTW I found it easier to unsolder the one leg than to "snip" it as some have suggested as there's hardly any room to get a "snipper" in there.

Anyone else do these Phase 90's and are there any other cool mods?? :fishing:

[tuberattler]

Man it is lonely in here! here! here! here! here! here! :fishing: :help:

[Mark Lavelle]

At least you've got the reverb working!

Egad - I just noticed that the level above Guitar Effects is Effectification - looks like ol' tboy has been nipping at the rat cheese again...

[David Schwab]

Here's one place.. they have two schematics:

http://www.tonepad.com/project.asp?id=7

[tele_guitarist]

Since I'm talkin to myself I found the modern Phase 90 Layout via a friend. It's at Youlsa.com which is in Korea. You'll have to Google and have them convert the page to English.

So, I modded the Phase 90 R28 by lifting one leg off the circuit board and wow what a great difference and pedal after the mod. Very usable!!

Now, why doesn't MXR make this pedal with out that resistor?? It's not very usable with it in the circuit..

BTW I found it easier to unsolder the one leg than to "snip" it as some have suggested as there's hardly any room to get a "snipper" in there.

Anyone else do these Phase 90's and are there any other cool mods?? :fishing:

I have a ton of other mods for them but they aren't free. http://www.guitartone.net/

bw

[David Schwab]

Since I'm talkin to myself I found the modern Phase 90 Layout via a friend. It's at Youlsa.com which is in Korea. You'll have to Google and have them convert the page to English.

So, I modded the Phase 90 R28 by lifting one leg off the circuit board and wow what a great difference and pedal after the mod. Very usable!!

Now, why doesn't MXR make this pedal with out that resistor?? It's not very usable with it in the circuit..

What does that mod do to the tone?

I used to have an old script logo unit, which I liked a lot. I see the new EVH model has a switch for the script sound, which it seems has less feedback than the newer ones.

[frankjc]

Where's the best place to find info on these pedals?

I'm trying to find a schemo or layout of the modern (new) Phase 90. I'm wanting to do the R28 mod that I've read about but I need a schem or picture or layout..something to locate the resistor in question.
What does this mod do?

[tele_guitarist]

What does this mod do?

It is one step of a conversion to script specs.

bw

[Mark Hammer]

A "real" phaser includes the following parametric controls:
1) rate/speed: self explanatory
2) resonance/feedback/emphasis/color: this adjusts how much of the output of the phase shift sections is fed back to the beginning to highlight/exaggerate the peaks and notches created
3) sweep width/depth: this adjusts how far the phaser sweeps upward from some predetermined starting point; the range of sweep
4) intensity/depth/mix/blend: this determines the relative proportion of phase-shifted and straight signal for subtler or more obvious effects, as wel as things like vibrato (phase-shift only)
5) initial/manual/offset: this determines the starting point of the sweep and frequency zone that the notches appear in; this is frequently linked to the depth/width control so that the less sweep width you set uit up for, the more latitude you have for manually adjusting where the sweep starts from

There are certainly more things that can be included but these provide the degree of flexibility needed to mimic a broad range of phaser sounds. A lot of commercial phasers are "one-knob wonders", like the P90/P45 and Small Stone, providing only speed control (#1). Others are 2 and 3 knob units, providing controls #1 and one or both of #2 and #3. A few have 4 controls and very few few have all 5.

The script/block changes pertain to a few things, but most especially to a preset amount of resonance. Think of the script-vs-block thing as if the 2 P90s each came with controls #1 and #2 and one version had control #2 tweaked a bit. I forget which version has which amount.

In general, less resonance is more suitable for rhythm playing, or subtler modulation, while higher resonance lends itself more to leads. Rather than merely changing the fixed resistor to produce a fixed amount, the unit should be reconfigured with a variable control to produce not only the presets but other amouts of resonance as well. This could be done by replacing the resistor in question (the 22k value shown in red here: http://www.tonepad.com/getFile.asp?id=42) with a 12k fixed resistor and 50k variable resistor in series. This will get sounds from even more resonance than either block or script to much subtler sounds; a far more flexible unit.

[David Schwab]

A "real" phaser includes the following parametric controls...

http://www.modezero.com/bitmaps/_maestro-ps1a-Ax.jpg


Ah... simplicity! :)

This was my first phase shifter... actually this was the first phase shifter. Built by Oberheim for Gibson from a circuit drawn on a napkin by Dave Rossum of E-MU Systems.

I always liked the script Phase 90... just had a nice sound. I prefer Flangers to have all the controls, but I don't mind Phase shifters with just speed... if they sound good.

Otherwise you need all the controls to get them to sound the way you want.

Nothing is worse than a one knob phaser with way too much feedback! Too much resonance and it sounds like a wah.

The Mutron Bi-Phase sounded good with the resonance up though.

:D

[tuberattler]

For those who've asked "what did the mod do?" here's the answer in layman terms.

The sound was too pronounced & strong stock, also there was some distortion coming in the sound when you leaned on it hard with your guitar or keyboard.

So, when I lifted the R28 from the circuit board it mellowed the pedal out a great deal. Now I could play it with my guitar and not sound silly. After the mod it sounded authentic and rich.

My keyboard guy now could play it and actually turn the knob whereas before he had the knob pegged in the CC position.

I don't know why they don't sell this pedal without that R28 installed as it sounds much richer, fuller, authentic & musical to my ears..HTH's

[David Schwab]

I don't know why they don't sell this pedal without that R28 installed as it sounds much richer, fuller, authentic & musical to my ears..HTH's

Well they make you buy the EVH model now for more money which has a switch for that mod.

[tele_guitarist]

Well they make you buy the EVH model now for more money which has a switch for that mod.

actually the evh model isn't just lifting the r28, it's alot more changes than that to get it to bonafide script specs. However, the evh sounds WONDERFUL.

[David Schwab]

I have a circuit board layout and parts list for a script Phase 90 I did some years ago. I had to repair one (an op amp went bad) so I took some time and drew it out. Later I also owned a script model that stopped working one day. Probably also been a part failure, but I never took the time to find the part.

I think I know where I put the diagram... I'll have to look for it.

I figured it might be a way to buy a new unit and mod it to script specs. I'd just build one myself, but I don't feel like checking/biasing all those FETs...

:)

[tele_guitarist]

I have a circuit board layout and parts list for a script Phase 90 I did some years ago. I had to repair one (an op amp went bad) so I took some time and drew it out. Later I also owned a script model that stopped working one day. Probably also been a part failure, but I never took the time to find the part.

I think I know where I put the diagram... I'll have to look for it.

I figured it might be a way to buy a new unit and mod it to script specs. I'd just build one myself, but I don't feel like checking/biasing all those FETs...

:)

I got it for ya ;)

From Nero1985, http://www.myspace.com/nero85 :

Hi!

Here you find out how to turn your Phase 90 that you just got a Guitar Center into the Script Phase 90 wich is not just a R28 mod or the C11 and C12 mods, it goes beyond that.
There are 8 components on the new P90s that werent on the Script logo used by Eddie Van Halen and many others, here you can see what components have to be removed and wich ones replaced.
Im also including a picture of its board with the component numbers so that u dont have to look for them all night long just to remove it or replace it!
The Script Mod was tested by me and worked amazing, you'll get a very nice phase that might not be great as a pre distortion pedal but if u run it on ur Fx loop of after a Tube Screamer (like i do) you'll a crazy Phase!
The OTHER MODS havent been tested but they should work fine.

It took me a hours to realize the structure of the new P90 so i hope it helps you....

http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_to_Script.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_board.sized.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90_Script.gif
http://aronnelson.com/gallery/albums/Schematics-etc/MXR_Phase_90.gif
http://aronnelson.com/gallery/albums/Schematics-etc/phase_90_board.sized.jpg

You can't really mod a block logo or reissue P-90 to script specs, as the circuits are too different (# of chips, etc). And there were more than one version of the script logo, with different numbers of chips. MXR used revision numbers on the boards, i.e. rev 108 came out in 1978, which rev is your mod? My 1974 P90 (Bud Box) has 6 chips in it as does my later 76 script logo.
in 1979 they changed from 741 chips (single op amps) to TL062 duals, so # of chips was reduced. You should replace the op amps with 1458 chips for a script mod.

Also: http://diy.erikhansen.net/phase90diff.htm

bw

[David Schwab]

I posted a reply.. and it vanished!

I had the old version with six 741 op amps, and the Bud case.

That's the one I diagrammed.

On the one I repaired, since I couldn't find which 741 went bad, I pulled all of them, installed sockets, and replaced them with TL071's.

Worked out real nice.

OK... So maybe I'll just build my own. :)

[Mark Hammer]

Eastern Washington? Is that near the town of George? Just curious.

Some folks want a phaser for wah-like cyclical emphasis, but some want it for gentler animation, and some - god help them - want it for both. That's why a **real** phaser has a control to vary it. The Small Stone had a 2-position Color switch that provided two resonance settings along with their corresponding sweep width setting. I suppose that gave it a big edge over the single-setting Phase 90.:rolleyes: The MXR Phase 100 leapfrogged over that and provided a 4-position switch that yielded combinations of two sweep width settings and two resonance settings.